OBSERVING SUNSPOTS

As the Sun rotates on its axis, you can watch a group of sunspots travel from one edge of the disk to the other over a period of about 10 days. A few long-lived spots will come around for a second period of visibility.

SUNNY SIDE UP

The most famous solar features are the sunspots. Records from China show that since ancient times, observers have noticed dark spots on the Sun. (These naked-eye observations were made when the Sun was low in the sky or partly obscured by fog, mist, or clouds. Do not try to copy their technique, however— many astronomers in antiquity probably went blind.)

SKETCHING SUNSPOTS

Sketching sunspots is easiest using the projection method. Decide on a standard size of sketch—6 inches (150 mm) is common—and prepare blank forms ahead of time with a circle for the Sun's diameter and places to note date and time, weather, seeing conditions, and the equipment you used.

SUNNY RADIO SIGNALS

Because most cosmic radio signals are very weak, radio astronomy demands large, sophisticated equipment. The Sun, however, the strongest radio source in the sky and this presents opportunities to the amateur with an interest in electronics.

DOES THE SUN VARY?

Compared to some stars, which can vary in apparent brightness by factors of a hundred or more, the Sun seems like constancy itself. On the other hand, there are those 11-year sunspot cycles. Furthermore, astronomical history shows that sunspots can virtually disappear for decades on end, with notable climatic consequences.